A class of superconducting magnet generating a highly uniform field is required for nuclear magnetic resonance (NMR) spectroscopy. The uniformity of the field requires accurate positioning of the turns of the superconductor coil in a precisely defined geometry. It also requires that proximity of the superconducting coil with materials having a magnetic susceptibility greater than zero be avoided. Thus, all ferrous alloys, including so-called "non-magnetic" stainless steel, must be eliminated from the structure and windings of the NMR magnet.
High field superconducting magnets typically use niobium-tin superconductor. The superconductor is wound in the form of a wire in which the component niobium and tin are in the unreacted state. The superconducting wire is wound around a form of suitable geometry to provide a superconducting coil. The form and coil are heated to approximately 700.degree. C., thereby forming the superconducting intermetallic niobium-tin compound, Nb.sub.3 Sn, mounted on the coil form. The high temperature reaction requires the use of refractory materials for the forms upon which the superconducting wire is coiled and heated. Copper, aluminum and their alloys, suitable for magnet applications, are unsuitable because of softening or melting near 700.degree. C. Similarly, organic materials can not be used. A refractory material, i.e., stainless steel, are preferred for the high temperature reaction of the superconducting coil but are unsuitable for NMR magnet applications. A stainless steel form is preferred for the high temperature reaction of the superconducting coils, while a non-magnetic material is preferred for the magnetic applications of the superconducting coils.
It is an object of the present invention to provide a superconducting coil and method for its manufacture on a non-magnetic form which does not disrupt the magnetic field of the superconducting magnetic.
It is a further object of the present invention to provide a coil form which is capable of assembly and disassembly and suitable for use at high temperatures for the preparation of superconducting coils.